Radiological risk assessment of some consumed cigarettes and hookah in Iraq

The main purposes of the research are to assess the radiological risk due to smoking cigarettes and hookah and their impacts on the people health. Radon levels were measured in 28 consumed brands of cigarettes and 10 brands of hookah consumed Iraq using CR-39 solid state nuclear track detectors (SSNTDs). The results showed that the 222Rn concentration in cigarette tobacco samples ranged from 138.9 to 781.2 Bqm-3 with average value of 318.0 Bqm-3. The radon concentrations emerged from 11brands of the investigated samples was significantly higher than the recommended value. While, its concentration in hookah ranged from 633.6 Bqm-3 to 416.6 Bqm-3 with average value of 509.5 Bqm-3. The Potential Alpha Energy Concentration (PAEC) in terms of (WL) units, Exposure to radon progeny (EP), and the annual effective dose (AED) in terms of (mSv/y) units were also obtained. Lung cancer cases per year per million people (CPPP) are also evaluated with an average value of 144.4 per million people. The result indicates that the average values of PAEC, EP and AED were within the recommended range values given by UNSCEAR, NCRP and ICRP respectively. The radioactive impact of smoking is considered as a risk factor for lung cancer.


Introduction
Tobacco is a cultivation production prepared from green leaves of plants in the genus Nicotania. Tobacco also consists of small amount of radioisotopes that cause a radiation exposure hazard to smokers and passive smokers. Most humans became aware that the smoke of cigarette and tobacco has many toxic substances for example tar, arsenic, nicotine and cyanide. The common risks of cigarettes have been recognized for years. Yet, few humans realize that tobacco also contains radioactive materials: polonium-210 and lead-210. The combination of the toxic and radioactive materials in cigarettes hurt smokers. They also hurt persons subjected to secondhand smoke. The radioactive isotope, Polonium-210, in cigarettes rests in "hot spotsˮ in the lungs is one of the reasons which cause cancer [1]. Polonium is an alpha emitter which has a very damaging impact on lungs tissues. Alpha particles are a double positive charge which has very high ionizing energy that expended in the lung tissues and travels a limited range in the materials which it interacts with [2]. During its movement through the lung tissues it can produce a great numbers of ion pairs which in turn may cause cancer and may lead to thousands of deaths a year. Since alpha particles can be stopped by the dead layer of the skin, then they are much less harmful than when they inter the blood stream, breathed in or ingested [3].
Smokers have the most serious danger of lung malignant growth. The danger of lung malignant growth increases with the length of smoking period and number of cigarettes consumed in a day. If they stopped smoking for a long time, they can lower the probability of malignant growth [4]. As indicated by the BEIR IV report of the US National Academies of Sciences and as per Pennsylvania Department of Environmental Protection, smokers were 10 and 6 times probable to get lung cancer than non-smokers, respectively. So, being a smoker is one of the factors that increase the possibility of developing radon induced lung cancer [5,6]. Radioactive material from tobacco smoke is considered as the 2 nd major reason of global death as reported by World Health Organization (WHO). In whatever the way of consuming tobacco will result in different amounts of radioactive material to be entered the smoker's bloodstream. This causes the smoker to be exposed to a level of radioactive material that in a time can lead to different type of diseases like cancer, ulcer, leukemia and many other ailments [7]. Therefore, many countries impose strict conditions such as a minimum smoking age, adjust the purchasing and using of tobacco merchandise. Hence, the perspective goals of this research are: (1) determination of radioisotopes level in most consumed brands of cigarettes in Iraq.
(2) Calculation of risk indices such as (The Potential Alpha Energy Concentration (PAEC) in terms of (WL) units, radon progeny exposure (RP), and the annual effective dose (EDA)). (3) To point up conclusions on hazardous impact of radioactivity due to smoking cigarettes and hookah.

Materials and methods
Twenty-eight different brands of cigarettes and10 hookah flavor samples were collected from cigarettes shops. Tables 1and 2 illustrate the coding of the studied cigarette and hookah flavor samples. Craven "A" CR UK 28 Philip Morris (blue) PM USA Five grams of each tobacco samples was put in plastic containers while the weight of each hookah flavor samples was 10 grams also put in plastic containers. The height of the container was 7.5 cm and 6.5 cm in diameter. A piece of CR-39 detector with area (1 x 1) cm 2 was sticked on the inside face of the container's cover ( Figure 1). Each sample was replicated 3 times. The containers were left at room temperature for two months exposure time. During this time alpha particles from the decay of radon, and its daughters fall on the CR-39 nuclear track detectors. Then, after the exposure time, alpha tracks on CR-39 detectors were developed using 6.25N NaOH etching solution at temperature 70°C for 5 h. After chemical etching Cr-39 pieces were washed with distilled water and prepared for counting the tracks with an optical microscope.
The concentration of radon in the study cigarette brand samples (CRn) was calculated by utilizing equation (2) suggested by Somogyi et al. [1986]. They proposed that the number of radon atoms emitted from the sample is equal to the number of radon atoms in the air above the sample times the decay probability, which can be written in the following form [13], [14]: Where: λ: decay constant for ( 222 Rn) , h: sample surface to detector distance (cm), t: time of exposure = 60 day, L: height of the sample (cm). The Potential Alpha Energy Concentration (PAEC) in terms of (WL) units was calculated utilizing equation (3) [ [15][16][17]: UNSCEAR (2000) proposed that (F) is the equilibrium factor between radon and its progeny and it is = 0.4. Equation (4) shows the relation between the exposures to radon progeny (EP) with the average radon concentration C [18]: Where C is in Bq.m -3 , n = 0.8 (the fraction of time spent indoors), 8760 = hours / year, 170 = number of hours /working month. Furthermore, the annual effective dose (AED) in units of (mSv/y) was also calculated using equation (5) [ [19][20][21]: Where H = 0.8 (the occupancy factor), T=8760 h.y -1 , and D = 9×10 -6 mSv / (Bq.h.m -3 ) (the dose conversion factor). Then (CPPP), which is the number of lung cancer cases per year per million people, was calculated using the following equation [16], [22], [23]: Table 3 displays the calculated values of C, CRn, PAEC, EP, AED and CPPP in the measured tobacco cigarette samples. Table 3 Radon gas concentration (C) in the can air above the samples, Radon gas concentration in the various brand tobacco samples (CRn), potential alpha energy concentration (PAEC), exposure to radon progeny (EP), annual effective dose (AED), and lung cancer cases per year per million persons (CPPP)  Figure 1 illustrates the results of C which perceives that the highest radon concentration was found in GL1 (Gauloises (gold) -France) with a value of (781.2 Bq.m -3 ), while the lowest radon concentration was (138.9 Bq.m -3 ) in WT2 (West (fusion black) -Germany) and PS1(P&S (black) USA), with an average value of (318.0 Bq.m -3 ), which is higher than the recommended range (200-300 Bq.m -3 ) [24]. Twelve out of twenty-eight cigarette samples are higher than the allowable value given by ICRP [24]. The dissolved radon concentration of the brands tobacco cigarette samples varies between 12.3×10 3 Bq.m -3 to 69.3×10 3 Bq.m -3 with an average value of 28.2×10 3 Bq.m -3 .  The annual effective dose (AED) received by the residents ranged from (3.504 mSv.y -1 ) to (19.708 mSv.y -1 ) with a mean value of (8.024 mSv.y -1 ). AED in all measured tobacco samples were lower than the recommended range (3-10 mSv.y -1 ) (ICRP, 1993) except SG2 (13.577 mSv.y -1 ), MS and OS1 (12.263 mSv.y -1 ) and GL1 with value (19.708 mSv.y -1 ). The results are shown in Figure 2. As well radon concentrations are positively correlated with CPPP as shown in Figure 3. Lastly, we can say that most of the obtained results presented in this study are comparable with the results given in previous studies made on some tobacco samples used in the Iraqi market [26], [27].

Hookah flavor samples
The measured values of C, CRn, PAEC, EP, AED and CPPP in the investigated tobacco cigarette samples are given in Table 4. Table 4 Radon gas concentration in the various brand hookah samples (CRn), potential alpha energy concentration (PAEC), exposure to radon progeny (EP), annual effective dose (AED), and lung cancer cases per year per million person (CP PP). The results reveal that the highest radon concentration was found in ZC (Zain, Castro -France) with a value of (633.6 Bq.m -3 ), while the lowest radon concentration was (416.6 Bq.m -3 ) in AM (Al Amasi -Germany), with an average value of (509.5 Bq.m -3 ), which is higher than the recommended range (200-300 Bq.m -3 ) [24]. The obtained results are shown in Figure 4.  The annual effective dose (AED) received by the residents varies from (10.511 mSv.y -1 ) to (15.985 mSv.y -1 ) with an average value of (12.854 mSv.y -1 ). AED in all measured hookah flavor samples are higher than the recommended range (3-10 mSv.y -1 ) [18]. The results of AED are shown in Figure 5. Hookah Sample's Code Figure 6 illustrates the positive correlation between the radon concentrations and CPPP for hookah samples. The present obtained results are higher than the results reported in the previous studies made on some hookah flavor samples used in the Iraqi market [29].

Conclusions
Tobacco smoking is lethal from numerous points of view and it has genuine wellbeing, financial, and social outcomes. Despite the fact that the common radioactive materials in tobacco and hookah can be considered as one of the fundamental purposes behind the health effects of smoking cigarettes or hookah, there are very restricted published researches on the concentration of natural radioisotopes in tobacco. Moreover, the concentration of radioactive isotopes content in tobacco differs within the same brands of cigarette as well as same brands of hookah. Furthermore, the measured radon concentrations in both tobaccos of cigarettes or hookah samples are found greater than the recommended range given by ICRP.
The estimated radiological impacts indices calculated in this work such as PAEC, EP and AED in most tobacco cigarette samples were found to be lower than the recommended value. While only 6 samples of hookah tobacco were found to be lower than the recommended value.
The excess lifetime cancer risks values estimated were also lower than the recommended limits given by ICRP except GL1 and SG2 cigarette samples and FM, ZC, RZ and DJ hookah samples. This represents a genuine malignant growth hazard and some other radiation wounds to the smokers and passive smokers in the environment. So, It can then be deduced that various factors, for example, the planting area where the tobacco plant is grown, the cultivation of the tobacco, the size and composition of the filter, manufacturing procedures, age of the products and smoking habits govern the degree of exposure via the path way of tobacco. From the present work we found that according to the International Commission of Radiological Protection, the results reveal that 16 of cigarette tobacco samples are within the allowable limits, while all the hookah tobacco samples are higher than the allowable limits. Hence, we can conclude that the radioactivity content in hookah products was higher than that of the cigarette products, so, hookah flavor may add risk of lung malignancy to that due to tobacco for smokers.